This invention relates to an apparatus for the automatic installation of expander rings into a circumferential ring groove of split piston rings, particularly oil scraping piston rings. The piston rings and the expander rings are stored in separate magazines and may be dispensed individually therefrom.
The preparation of piston rings requires a significant number of different, mutually coordinated processes. In case of large numbers of piston rings to be prepared, the output is dependent from the working speed of the individual processes. For treating the running faces, the piston rings are, for example, polished in a polishing (lapping) sleeve. The discontinuous piston ring exerts a radially outwardly directed force so that it engages the inner circumferential surface of the polishing sleeve with a defined inherent stress which depends from the ring geometry. Based on such a geometry, in some piston rings the inherent stress is insufficient for providing a satisfactory treatment of the running faces. For this reason, in piston rings having only a slight inherent stress, expander rings are inserted into the inner ring groove. Since such a process is conventionally performed manually, the manufacturing costs are very significantly increased.
German Offenlegungsschrift (application published without examination) 24 40 996 discloses an apparatus for installing split safety rings into ring grooves of cylindrical workpieces. The safety rings to be installed are stored in a stacked state in a magazine and are individually ejected therefrom for insertion on a spreader mandrel. The installation of spreader rings into piston rings, however, cannot be performed with such an apparatus.